Methine dyes



United States Patent 3,232,933 lVfETl-lll E DYES .lean Marie Nys and Henri Deloorter, Mortsel-Antwerp,

Belgium, assignors to Gevaert Photo-Producten N.V.,

lviortsei, Belgium, a Belgian company No Drawing. Filed Dec. 19, 1969, Ser. No. 76,525 Claims priority, application Great Britain, July 5, 1957,

21,353/57 5 Claims. (Cl. 260-2456) This application is a continuation-in-part of our application Serial No. 745,347, filed July 3, 1958, now abandoned.

This invention relates to new methine dyes and to their preparation and use as sensitizers for photographic silver halide emulsions, and to methods of sensitizing such emulsions by means of such sensitizing dyes.

A great number of methine dyes are known and many of them have been found to sensitize photographic emulsions in a variety of useful manners. These sensitizing polymethine dyes, however, when used in such emulsions leave in general a residual stain in the colloid imagebearing layers and/or in other photographic layers such as sub-layers or even in the film support of developed and fixed photographic elements. The staining effect is particularly troublesome in the case of photographic elements which are used in photo-mechanical processes, for example photographic negatives of the lithographic type which are to be corrected subsequently by a color mask image, and therefore a neutral tint is an absolute requirement. This staining effect is furthermore particularly objectionable in photographic papers since it is impossible, when suchdye-sensitized emulsions are used, to obtain bright whites in a black-and-white picture or a true reproduction of the colors in a color picture. A light rose or yellow residual stain may further cause trouble when a finished photograph is exposed partly to full daylight, the other part being covered, so that under the influence of light the residual dye-stuff can bleach out, leaving an image which is partly white and partly colored.

It is therefore very important, when sensitizing photographic emulsions by dyes, to avoid this residual staining effect in finished photographic papers, in films of the litographic type or other finished photographs in which such stain is objectionable.

It is an object of the present invention to provide a new class of methine dyes which do not leave a residual stain in developed and fixed photographic elements. A further object is to provide methods for preparing these new dyes. Still another object is to provide silver halide emulsions sensitized with these new dyes. A still further object is to provide a practical and useful method for sensitizing silver halide emulsions which has the great advantage that, when such emulsions are coated on a suitable support, the exposed photographic element after development and fixing gives a finished photograph which is essentially free from any residual stain. Other objects will become apparent from a consideration of the description and examples.

It is common knowledge that the methine dyes are adsorbed on the silver halide crystals and on the particles of the colloid binder along the organic residue attached to the auxochrome nitrogen atom, that is the cyanine nitrogen atom which is linked through a conjugated carbon chain to another auxochrome group such as for example a nitrogen atom or a carbonyl, thiocarbonyl or cyano group.

it has now been found that sensitizing methine dyes, which are adsorbed on the silver halide crystals and on the hydrophilic water-permeable colloid binder along li ateniecl Nov, 1936 an organic residue bearing a hydrophilic group containing a sulphonamide grouping generally do not leave an objectionable residual stain in the photographic layers after development and fixing of the exposed photographic element has been completed, independently of the watersolubility of the new methine dyes involved. It has been found indeed that by introducing in the molecule of the methine dye an organic residue containing a hydrophilic group according to the invention, the residual stain is avoided, although in many cases the water-solubility of the new dyes is not markedly changed and in some cases even diminished. In this way it was surprisingly discovered that some new monomethine cyanine dyes which contain an organic residue bearing a hydrophilic group according to the invention are considerably less water-soluble than the corresponding alkyl substituted dyes, but nevertheless left no residual stain in the finished photograph. The readiness with which the new methine dyes can be removed from the exposed photographic element during processing consequently has no direct relation with the solubility of the dyes involved but is or may be regarded as a result of a desorption phenomenon whereby in aqueous medium the dye molecules are withdrawn from the surface of the silver halide crystals and/or the particles of the colloid binder on account of the great water-afiinity of the organic residues containing the hydrophilic groups according to the invention. The existence of such desorption phenomena is known from adsorption chromatographic separation techniques Where the solubility does not play a preponderant role either.

It is further known that methine dycs containing electronegative groups in general are relatively poor sensitizers for photographic emulsions or even desensitizers for such emulsions and therefore not useful as practical photographic sensitizers.

It has now been found that the sensitizing power of the new methine dyes, which contain an organic residue bearing a hydrophilic group containing a sulphonamide grouping, is not markedly reduced notwithstanding the high electronegative value of the hydrophilic groups involved.

We have also found that the introduction into methine dye of such an organic residue bearing a hydrophilic group containing a sulphonamide grouping may in some cases result in a shifting of the sensitization spectrum to the shorter wave-lengths. In the case of orthochromatic emulsions this hypsochrome shifting may be very desirable to allow an extension of the spectral composition of the light in the darkroom to physiologically clearer, that is shorter wave-lengths without the risk of fogging the emulsion; such an extension is inter alia required when treating photographic elements used for copying and/or photo mechanical processes. If this shifting is undesirable, it can be remedied by adaption of the other elements constituting the methine dye, for example by changing a heterocyclic nucleus or by introducing a substituent in a nucleus or in the conjugated chain.

According to the present invention we provide new sensitizing methiue dyes wherein at least one cyanine nitrogen atom bears an organic residue containing a sulphonamide grouping which is connected with the nitrogen atom through an alkylene radical, more particularly, an organic residue of one of the following formulae:

-AlkyleneCONH-ASO B n and wherein A represents e.g. a hydrogen atom, a hydrocarbon radical such as an alkyl group, an amino group, wherein the hydrogen atom may be substituted e.g. by an alkyL or acyl-group, an acyl-group, and an alkyl sulphonyl group, and B represents e.g. an hydrocarbon radical such as an alkyl group, or an amino group wherein the hydrogen atom may be substituted e.g. by an aikylor acyl group. By intramolecular ionization the organic residue attached to the nitrogen atom may have a structure such as According to a further feature of the present invention we provide a photographic silver halide emulsion sensitized by incorporating therein at least one of the new methine dyes as hereinbetore defined. The present invention further includes a process for preparing high-sensitive photographic silver halide emulsions which give, after development and fixing of the exposed photographic element, a finished photograph which is essentially free from any residual stain which comprises treating a photographic silver halide emulsion with a sensitizing methine dye as hereinbefore defined, and a light-sensitive photographic element containing at least one silver halide emulsion layer sensitized according to the foregoing process.

The present invention also includes a method of preparing the new methine dyes, which method consists in treating a quaternary salt of a heterocyclic nitrogen base bearing at the nitrogen atom an organic residue of one of the above Formulae I, II or III, by one of the methods known to be capable of converting the quaternary salt of such heterocyclic base into a methine dye. The word known is to be understood as designating methods in actual use or described in literature on the subject.

The quaternary salts employed in the present invention can be obtained by treating the corresponding heterocyclic nitrogen base with a compound of one of the general formulae:

X-AlkyleneCONHSO -B (11") and XAlkyleneNH%O B 111" wherein X represents an acid residue such as for example a halogen atom such as Cl and Br, and A and B have the same significance as set forth hereinbefore. The heterocyclic nitrogen base and the compound of Formulae I", II" or III" above are merely heated together to form the quaternary halide. Crude quaternary halides prepared in this manner may be converted, if desired, into other quaternary salts before employing them to prepare our new methine dyes.

The following preparations will serve to illustrate the method for preparing the intermediate compounds of the Formulae I", II" and III".

PREPARATION 1.-3-BROMO-PROPANE-SULPHO- NYL CHLORIDE Finely pulverized 3-bromo-propane sulphonic acid sodium salt (275 g.) is slowly added, whilst cooling and stirring, to phosphorus pentachloride (276 g.). Next the mixture is kept for one hour at room temperature and then heated for two hours upon a water bath at 7080 C. After cooling overnight at room temperature the reaction mixture is poured out, whilst stirring, into 700 g. of ice. Stirring is continued until complete conversion of the phosphorus oxychloride formed into phosphoric acid and dissolution of the sodium chloride formed is obtained. The sulphochloride is dissolved in ether and dried upon magnesium sulphate. After evaporation of the ether, the sulphochloride is distilled in vacuum.

Boiling point: 98 C. at 2 mm. Hg.

3-bromo-propane sulphonyl chloride may also be prepared according to R. Adams and Campbell, I. Am. Chem. Soc. 72 (1950), 131, via the 3-b-romo-propylthiocyanate with the disadvantage, however, of considerable decomposition on distillation and with a poor yield.

PREPARATION 2.3-BROMO-PROPANE- SULPHONAMIDE A solution of 3-bromo-propane sulphonyl chloride (25 g.) in 250 cm. of anhydrous ether is treated at 0 C., whilst stirring, with dry ammonia gas until no more ammonia is absorbed. The ammonium chloride formed is filtered ofif and washed with acetone. After evaporation of the solvent, crude 3-bromo-propane-sulphonamide is left and is recrystallized from a mixture of benzene and petroleum ether. Melting point: 60 C.

PREPARATION 3.N-ACETYL-3-BROMO- PROPANE-SULPHONAMIDE 3-bromo-propane-sulphonamide (7 g.) and acetic anhydride (5.2 cm. are heated for one hour upon a boiling water bath. On cooling, the mass crystallizes out. After recrystallization from a mixture of benzene and petroleum ether, the acetylsulphonarnide melts at 93 C.

PREPARATION 4.4-BROMOBUTANE- SULPHONYL CHLORIDE This compound is obtained from phosphorus pentachloride (212 g.) and 4-bromo-butane sulphonic acid sodium salt (212 g.) by proceeding as for preparation 1. Boiling point: 128 C. at 2.5 mm. Hg.

PREPARATION 5.4-BROMO-BUTANE- SULPHONAMIDE This compoiind is prepared analogously to preparation 2 from 4-bromo-propane-sulphonyl chloride. Melting point: 68 C.

PREPARATION 6.N-ACETYL-4-BROMO- BUTANE-SULPHONAMIDE BrCH CH CI-I CH SO NHCOCH This compound is prepared analogously to preparation 3 from 4-bromo-butane-sulphonamide (10.5 g.) and acetic anhydride (7.5 cm. Melting point: 88 C.

Methane sulphonamide (4 g.) is dissolved in 20 cm. of Water. After cooling at 5 C. 5 N sodium hydroxide (16.8 cm?) and 3-bromo-propane sulphonyl chloride (9 g.) are added simultaneously and drop by drop whilst stirring taking care to keep the pH at 8. This step lasts about three hours and stirring is continued for a further twenty minutes. Next the solution is acidified with strong hydrochloric acid (4.2 cm?) and evaporated under reduced pressure. The residue is extracted with acetone and after removing the solvent N-methylsulpho-3-bromopropane sulphonamide is left. Melting point: 72 C.

PREPARATION 9 .-N- BROMO-ACETYL METI-IANE SULPHONAMIDE Methane sulphonamide (72 g.) together with bromoacetyl bromide (208 g.) are gradually heated to 100 C. and kept for one hour at this temperature. If the hydrobromic acid development is too intense at the beginning, heating can be interrupted. The mass crystallizes on cooling, is dissolved in warm benzene and filtered from a small amount of oily product. On cooling, the pure product crystallizes. Melting point: 110 C.

PREPARATION lN-(BROMO-ACETYL)- ETHANE SULPHONAMIDE Ethane sulphonamide (4.8 g.), bromo-acetyl bromide (12 g.) and dry benzene (25 0111. are refluxed until after about three hours no further hydrobromic acid escapes. After cooling and adding some petroleum ether, the product is sucked ofi and recrystallized from benzene. Melting point: 104 C.

PREPARr TION 11.N-(BETA-BROMO- PROPIONYL) -METHANE SULPHONAMIDE Methane sulphonamide (8.06 g.) together with betabromo-propionyl chloride (19.2 g.) are graduallly heated to 110 C. At 100 C. the reaction sets in with evolution of hydrochloric acid. Heating is continued for one hour at 110 C. Next the mixture is cooled, washed with benzene and purified by recrystallization from benzene. Melting point: 130 C.

PREPARATION 12.-N- BETA-BROMO-ETHYL METHANE SULPHONAMIDE H CSO NHCH -CH Br Methane sulphonyl chloride (29 g.) is added drop by drop, at a temperature of 10 C., to a solution of bromo-ethylamine hydrobromide (51 g.) in pyridine (100 cm. After ice-cooling the crystallized pyridine hydro bromide is filtered off and the filtrate is evaporated in vacuum. The residual oil is then extracted with acetone; the acetone extract is filtered off and evaporated. Melting point: 49 C.

PREPARATION 13 .-4-BROMO-BUTANE- SULPHOHYDRAZIDE 4-bromo-butane-sulphonyl chloride (23.5 g.) is dissolved in anhydrous dioxane (100 cm. Whilst stirring hydrazine (6.4 cm?) is added at 0 C., the stirring is continued for one hour at this temperature. Next the hydrazine hydrochloride is sucked off and the dioxane is removed in vacuum. The product is obtained as a white oil.

PREPARATION l4.-N-DIACETYL4-BROMO- BUTANE-SULPHOHYDRAZIDE Br--CHgOH:OHz-CHzSOgNHN C 0 CH3 To 4-bromo-butane-sulphohydrazide (31.7 .g.), acetic anhydride (31.7 cm. is gradually added without cooling.

After standing for a few days the reaction mixture is heated for one hour on a boiling water bath. After cooling the product is precipitated with n-hexane and recrystallized from a mixture of benzene with n-hexane. Melting point: 116 C.

PREPARATION 15 .N- (BROMOACETYL) -N',N'- DIMETHYLSULPHAMIDE N,N-dimethylsulphamide (186 g.), bromo-acetyl bromide (309 g.) and dry benzene (2 l.) are gradually brought whilst stirring at reflux temperature and then kept at this temperature until the evolution of I-IBr stops (10 15 hours). The mixture is filtered while hot and the residue extracted with two portions (500 cm?) of benzene. The filtrates are cooled and hexane (3 l.) is added, first slowly until crystallization sets in, then rather quickly. The product is purified by crystallization from benzene. Melting point: 84 C.

As suitable heterocyclic nitrogen bases, known to be convertible in a polymethine dyestulf, may be mentioned the heterocyclic nitrogen bases containing in the alpha or gamma-position to the nitrogen atom of the heterocycylic ring an alkyl, thioalkyl, beta-alkylthiovinyl, betahalogenvinyl, beta(N-methylanilino)-viny1 or beta-acylanilidovinyl group, which vinyl groups may carry a substituent.

While the process of preparing the quaternary halides is subject to variation particularly in respect of the nature of the heterocyclic nitrogen bases, the nature of the compounds of the general Formulae I", II" and III", the proportions of the reactants, the temperature, the time of reaction and the methods of isolation and purification of the quaternary halides, the following examples will serve to illustrate the method for preparing the quaternary halides.

PREPARATION 16.--2,4-DIMETHYL 3 (OMEGA- SULPHONAMIDE-PROPYL) THIAZOLIUM BRO- MIDE 2,4-dimethyl-thiazole (4.8 g.) and 3-bromo-propaue sulphonamide (8.1 g.) are heated together for twelve hours at C. After cooling and washing with ether, the mixture is dissolved in ethanol with a little water and reprecipitated with ether. Melting point: 224 C.

PREPARATION 17.2-METHYL 3 (OMEGA-ACE- T'YLSULPHONAMIDO PROPYL) 5 PHENYL- BENZOXAZOLIUM BROMIDE 2methyl-S-phenyl-benzoxazole (2.8 g.) and N-acetyl- 3-bromo-propane sulphonamide (3.3 g.) are heated together for twelve hours at C. The reaction product is then cooled and Washed with acetone. Melting point: 270 C.

PREPARATION 18.2 METHYL-3-(OMEGA SUL- PHONAMIDE BUTYL) BENZOTHIAZOLIUM BROMIDE 4-bromo-butane sulphonamide (19 g.) and Z-methylbenzothiazole (14 g.) are heated together for twelve hours at 100 0., whereby the reaction mixture is completely solidified. After washing with ether, the melting point is 243 C.

PREPARATION l9.2-METHYL 3 (OMEGA-ACE- TYLSULPHONAMIDO BUTYL) BENZOTHI- AZOLIUM BROMIDE I N-acetyl-4-brorno-butane sulphonamide (8 g.) and 2- methylbenzothiazole (6 g.) are heated together for twelve hours at 100 C. The reaction mixture is then cooled and washed with ether. Melting point: 234235 C.

I? PREPARATION 20.2 METHYL 3 (OMEGA- ETHYLSULPHONAMIDO BUTYL) BENZOSEL- ENAZOLIUM BROMIDE Z-methylbenzoselazole (3 g.) and N-ethlyl-4bromobutane sulphonamide (3.5 g.) are heated together for twelve hours at 95 C. After cooling, the reaction mixture is washed with acetone and ether.

PREPARATION 21.2-METHYL 3 [OMEGA-(N- METHYLSULPHO SOLPHONAMIDO)PROPYL]- BENZOTHIAZOLIUM BROMIDE N-methylsulpho-3-bromo-propane sulphonamido (2 g.) and Z-methyl-benzothiazole (2 g.) are heated for twenty hours at 100 C. The reaction mixture is cooled and washed with ether. Melting point: 180 C.

PREPARATION 22.-2-METHYL-3 (N-M'ETHYLSUL- PHO CARBAMYL METHYL) BENZOT'HIAZO- LIUM BROMIDE Z-methylbenzothiazole (15 g.) and N-(bromo-acetyl) methane sulphonamide (18 g.) are heated for eighteen hours at 100 C. After cooling, the reaction mixture is washed with acetone and ether. Melting point: 188 C.

PREPARATION 23.2-methyl 3 (N-METHYLSUL- PHO CARBAMYL METHYL) BENZOSELENA- ZOLIUM BROMIDE N-(-bromo-acetyl)methane sulphonarnide (15 g.) and Z-methylbenzoselenazole (15 g.) are mixed and heated for twelve hours at 100 C. After cooling, the reaction mixture is washed with ether. Melting point: 104 C.

PREPARATION 24.2 METHYL-3-(N-ETHYLSUL- PHO CARBAMYL METHYL) BENZOTHIAZO- LIUM BROMIDE N-(bromo-acetyD-e-thane sulphonamide (2 g.) together with Z-methyl-benzothiazole (2 g.) are heated for twelve hours at 100 C. After cooling, the mixture is washed with ether and dissolved in n-propanol. This solution is poured out, whilst stirring, into an excess of ether. The precipitated product is sucked ofi. Melting point: 170 C.

PREPARATION 25 .--2 METHYL 3 [BETA (N- METT-IYLSULPHO CARBAMYL) ETHYL]- BENZOTHIAZOLIUM BROMIDE N-(beta-bromopropionyl)methane sulphonamide (5.8

g.) and Z-methyl-benzothiazole (4 g.) are heated together for sixty hours at 100 C. After cooling and washing with ether, the quaternary salt is obtained. Melting point:

PREPARATION 26.2 METHYL 3 [BETA (N- METHSULPHO CARBAMYL) ETHYL] BEN- ZOSELENAZOLIUM BROMIDE N-(beta-bromopropionyl)methane sulphonamide (8.5 g.) and Z-methyl-benzoselenazole (8.2 g.) are heated to- .gether for sixty hours at 100 C. After cooling, the mixture is pulverized under ether and thoroughly washed with the same solvent. Melting point: 102 C.

PREPARATION 27.2:5 :6 TRIMETHYL 3 (N- METHYLSULPHO CAR BAMYL M E T H Y L BENZOTHIAZOLIUM BROMIDE N-(bromo-acetyDmethane sulphonamide (6 g.) and 2:5 :6-trimethyl-benzothiazole (5.5 g.) are heated for twelve hours at 100 C. After cooling, the reaction mixture is washed with ether. Melting point: 114 C.

PREPARATION 28.2 METHYL 3 (N-METHYL- SULPHO CARBAMYL METHYL) PHENYL- BENZO-XAZOLIUM BROMIDE N-(bromo-acetyl)methane sulphonamide (7.2 g.) and 2-methy1-5-phenyl-benzoxazole (7 g.) are mixed and heated for twelve hours at 100 C. After cooling the reaction mixture is washed with ether. Melting point: 124 C.

PREPAMTION 29.2 METHYL 3-(BETA-METH- YLSULPHONYLAMINO ETHYL) BENZOTHIA- ZOLIUM BROMIDE N-(beta-bromo-ethyl)methane sulphonamide (20 g.) and Z-methylbenzothiazole (15 g.) are heated in a sealed tube for sixteen hours at 120 C. After cooling, the solid mass is washed with ether and acetone. Melting point: 150 C.

PREPARATION 30.2,6-DIMETHYL 3 (OMEGA- ACETYLSULPHONAMIDO PROPYL) BENZO- THIAZOLIUM BROMIDE 2,6-dimethylbenzothiazole (10 g.) and N-acetyl-3 bromo-propane sulphonamide (14.5 g.) are heated together at C. overnight. After cooling and washing with ether, the mixture is dissolved in propanol and precipitated with anhydrous ether. Melting point: 218 C.

PREPARATION 31.1 ETHYL 2 METHYL 3- (OMEGA ACETYLSULPI-IONAMIDO-BUTYL) 5, 6-DICI-ILORO BENZIMIDAZOLIUM BROMIDE 1-ethy1-2-methyl-5,6-dichloro-benZirnidazole (9 g.) and N-acetyl-4-bromo-butane sulphonamide (9 g.) are heated together for twenty hours at 100 C. After cooling, the product is washed with ether. Melting point: 225226 C.

PREPARATION 32.2,4 DIMETHYL 3-(N-METH- YLSULPHO CARBAMYL METHYL) THIAZO LIUM BROMIDE PREPARATION 33.-2,5 DIMETI-IYL-3-(N-METH YLSULPHO-CARBAMYL METHYL)BENZOTHI- AZOLIUM BROMIDE 2,5-dimethyl-benzothiazole (9.5 g.) and N-(bromoacetyl)methane sulphonamide (10 g.) are heated overnight at 100 C. After cooling the product is washed with ether.

PREPARATION 34.2 METHYL 3 [BETA (N- METHYLSULPHO CARBAMYL) ETHYL] 5- CHLOROBENZOTHIAZOLIUM BROMIDE 2-methyl-S-chlorobenzothiazole (11 g.) and N-(betabromo-propionyl)-methane sulphonamide (11.5 g.) are heated for twenty-four hours at C. The reaction mixture is cooled and washed with ether. Melting point: C.

PREPARATION 35 .2 METHYL 3 (OMEGA-DI- ACE'I'YLSULPHOHYDRAZIDOBUTYL) BENZO- TI-IIAZOLIUM BROMIDE Z-methyl-benzothiazole (3.3 g.) and N-diacetyl-4-bromobutane-sulphohydrazide (6.3 g.) are heated together overnight at 115 C. After cooling and washing with ether the quaternary salt is dissolved in ethanol and precipitated with a mixture of ether and acetone.

PREPARATION 36.1 (BETA-METHYLSULPI-ION- YLAMINO-ETHYL -QUINALDINIUM BROMIDE Quinaldine (4.3 cm?) and N-(beta-bromo-ethyD- methane sulphonamide (6 g.) are heated together at 100 C. for 16 hours, cooled and Washed with ether. Melting point: 226 C.

PREPARATION 37.-2 METHYL 3 (N-DIMETH- YLAMINO-SULPHOCARBAMYL METHYL) -BEN- ZOTHIAZOLIUM BROMIDE Z-methylbenzothiazole (10 cm?) and N(bromoacetyl)- N,N'-di-methylsulphamide (13.3 g.) are heated together at 60 C. for 24 hours, cooled, pulverized, washed several times with acetone and twice with a little ethanol.

ing point: 160 C.

PREPARATION 38.2 METHYL 3 (OMEGA- ACETYLSULPHONAMIDO PROPYL) BENZO- THIAZOLIUM BROMIDE Z-methyl-benzothiazole (3 g.) and N-acetyl-4-bromopropane sulphonamide (4.8 g.) are heated together at 105 f C. for 24 hours, cooled, Washed with acetone and ether. Melting point: 260 C.

PREPARATZON 39.2,5 DIMETHYL 3-(N-METH- YLSULPHOCARBAMYL ETHYL) BENZOTHIA- ZOLTUM BROMIDE 2,5-din1ethyl-henzothiazole g.) and N-(beta-bromopropionyl)methane-sulphonamide (11.5 g.) are heated together at 105 C. for 24 hours, cooled, pulverized and washed with ether. Melting point: 204 C.

PREPARATION 40.2,5,6-TR1METHYL-3-(OMEGA- ACETYL SULPHONAMIDO BUTYL)-BENZOX- AZOLIUM BROMIDE 2,5,6-trimethyl-benzoxazole (5 g.) and N-acetyl-4- bromobutane-sulphonamide (7.74 g.) are heated together at 120 C. for 36 hours, cooled, washed with acetone and ether. Melting point: 2l3-2l4 C.

PREPARATION 4-1 .2 (BETA ANILINO-VINYL)- 3 (OMEGA-ACETYL-SULPHONAMlDO-BUTYL)- 5,6-DIMETHYL-BENZOXAZOLIUM BROMIDE 2,5,6 trimethy1-3-(omega-acetylsulphonamido-butyl)- benzoxazolium bromide (4.2 g.) and diphenyl-formamidine (3 g.) are heated at 135 C. for minutes, cooled and washed with acetone. Melting point 187 C.

PREPARATION 42.2,5,6 TRIMETHY L 3 (N- lNlETHYLSULPI-IOCARBAMYL METHYL)-BEN OXAZOLIUM BROMIDE 2,5,6-trimethyl-benzoxazole (8.8 g.) and N-(bromoacetyl)-rnethane-sulphonamide (10.8 g.) are heated at 85 C. for 6 hours, cooled, dissolved in tetrahydrofurane (2O cm. and precipitated with ether (20 0111. Melting point: l74l76 C.

As stated hereinbefore, the new methine dyestuffs according to the present invention may be obtained starting from the new heterocyclic quaternary salts by application of the usual condensation methods known to those skilled in the art.

The following description of some methods for preparing the new methine dyes is not complete and therefore is not to be regarded as limiting the scope of our invention but merely as a survey of the most usual condensation methods.

The new asymmetric cyanine dyes according to the present invention can he prepared by condensing a cyclammonium quaternary salt of the following formula:

Meltwherein Z represents the non-metallic atoms necessary to complete a heterocyclic nitrogen nucleus containing 5 to 6 atoms in the heterocyclic ring, of the type contained in cyanine dyes, such as those selected from the group consisting of those of thi-azole series (cg. thiazole, 4methylthiazole, 4-phenylthiazole, S-methylthiazole, S-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, 4-(2-t'hienyl)-thiazole, etc.), those of the benzothiazole series (e.g. benzothiazole, 4-chlorobenzothiazole, S-chlorobenzothiazole, 6-chlorohenzothiazole, 7-chlorobenzothiazole, 4-methylbenzothiazole, S-methylbenzothiazole, 6-methylbenzothiazole, 5,6-dimethylbenzothiazole, S-bromohenzothiazole, 6-bromobenzothiazole, 4-phenylbenzothiazole, S-phenylbenzothiazole, 4-methoxybenzothiazole, S-methoxybenzothiazole, 6-methoxybenzothiazole, S-iodobenzothiazole, 6-iodobenzothiazole, 4-ethoxybenzothiazole, S-ethoxybenzothiazole, 4,5,6,7-tetrahydrobenzothiazole, 5,6-dimethoxybenzothiazole, 5,6-dioxymethylene-benzothiazole, S-hydroxybenzothiazole, 6-hydroxybenzothiazole, 5,6-dimethylbenzothiazole etc.), those of the naphthothiazole series (e.g. alpha-naphthothiazole, beta-naphthothiazole, S-methoXy-beta-naphthothiazole, 5-ethoxybeta-naphthothiazole, 8-methoxy-alpha-naphthothiazole, 7-rnethoxy-alpha-naphthiothiazole, etc.), those of the thionaphtheno-7'.,6,4,S-thiazole series (e.g. 4-methoxythionaphtheno-7,6',4,5-thiazole etc.), those of the oxazole series (e.g. 4-methyloxazole, S-methyloxazole, 4 phenyloxazole, 4,5-diphenyloxazole, 4-ethyloxazole, 4,5-dimethyloxazole, S-p henyloxazole, etc.), those of the benzoxazole series (e.g. benzoaxozole, S-chlorobenzoxazole, S-methylhenzoxazole, 5-phenylbenzoxazole, fi-methylbenzoxazole, 5,6-dimethylbenzoxazole, 4,6-dimethylbenzoxazole, S-methoxybenzoxazole, 6- methoxybenzoxazole, S-hydroxybenzoxazole, 6-hydroX- ybenzoxazole, etc.), those of the naphthoxazole series (e.g. alpha-naphthoxazole, beta-naphthoxazole, etc.), those of the selenazole series (e.g. 4-rnethylselenazole, 4-phenylselenazole, etc.), those of the benzoselenazole series (e.g. benzoselenazole, S-chlorobenzoselenazole, S-methoxybenzoselenazole, S-hydroxybenzoselenazole, 4,5,6,7-tetrahydrobenzoselenazole, etc.), those of the naphthoselenazole series (e.g. alpha-naphthoselenazole, beta-naphthoselenazole, etc.), those of the thiazoline series (e.g. thiazoline, 4-methylthiaz0line, 4hydroxy methyl-4-methylthiazoline, 4,4-bis-hydroXymethyl-thiazoline, 4-acetoxymethyl-4-methylthiazoline, 4,4-bis-acetoxymethyl-thiazoline, etc.), those of the thiazolidine series (e.g, 2-benzthiazolylidene 4 thiazolidon etc.), those of the ox azoline series (e.g. oxazoline, 4-hydroxymethyl-4-methyl-oxazoline, 4,4-bis-hydroxyrnethyl-oxazoline, 4-acetoXymethy1-4-methyl-oxazoline, 4,4-bis-acetoXy-methyl-oxazoline, etc.), those of the oxazolidine series, those of the selenazoline series (e.g. selenazoline), those of the 2-quinoline series (e.g. quinoline, 3- methylquinoline, S-methylquinoline, 7-rnethylquinoline, S-methylquinoline, 6chloroquinoline, 8-chloroquinoline, 6-methoxyquinoline, 6-ethoxyquinoline, 6-hydroX- yquinoline, S-hydroxyquinoline, etc.), those of the 4- quinoline series (e.g. quinoline, 6-methoxyquinoline, 7- methylquinoline, S-methylquinoline, etc.), those of the l-isoquinoline series (e.g. isoquinoline, 3,4-dihydroisoquinoline, etc.) those of the 3-isoquin-oline series (eg. isoquinoline, etc.), those of the 3,3-dialkylindolenine series (etg. 3,3-dimethylindolenine, 3,3,5-trimethylindolenine, 3,3,7-trimethylindolenine, etc.), those of the pyridine series (eg. pyridine S-methylpyridine, etc.), those of the benzimidazole series (e.g. l-ethylbenzimidazole, l-phenylbenzimidazole, 1-ethy1-5,6-dichlorobenzimidazole, 1-ethyl 3 hydrOXyethyl-S,6-dichlorobenzimidazole, 1-phenyl-5,6-dichlorobenzimidazole, l-ethyl- S-chlorobenzimidazole, l-ethyl 5-6 dibromochlorobenzimidazole, etc.);

X represents an acid radical of the type used in the cyanine dyes such as chloride, bromide, iodide, perchlorate, benzenesulphonate, p-tolusulphonate, methylsulphate, ethylsulphate, etc.;

n represents 1 or 2; and

R represents an organic residue containing a sulponamide grouping and corresponding to one of the Formulae I, II and III above, more particularly an organic radical of one of the formulae A represents a hydrogen atom, a lower alkyl radical such as methyl and ethyl, an amino group, a diacyl amino group such as a diacetylamino group, an acyl group such as an ecetyl group, or an alkylsulponyl group such as a methylsulphonyl group, and p represents a positive integer from 4 to 5,

B represents a lower alkyl group such as methyl and ethyl, or a dialkylamino group, such as a dimethyl or diethylamino group, a diacyl-amino group such as a diacetylamino group, and

wherein q represents a positive integer from 2 to 3, with a cycl-ammonium quaternary salt represented by the following formula:

wherein Z" represents the non-metallic atoms to complete a heterocyclic nucleus containing 5 to 6 atoms in the heteroeyclic ring of the type contained in cyanine dyes such as those described for Z;

n" reprwents 1 or 2;

X" represents an acid residue;

R" represents a radical of the type contained in cyanine dyes as substituent on the cyanine nitrogen atom, e.g. an alkyl or substituted alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, allyl (vinyl methyl), beta-hydroxyethyl, benzyl (phenyl methyl), carboxybenzyl, a radical containing a sulphonamide grouping such as a radical of the same type as the radical R defined hereinbefore, a radical containing a sulpho-alkyl carbonylic ester group, etc. (e.g. an alkyl group of the formula C H wherein r represents a positive integer from 1 to 4), an aryl group such as phenyl, carb-oxyphenyl etc. (e.g. a monocyclic aryl group of the benzene series); and

D represents an alkyhnercapto, an arylmercapto, a betaarylaminovinyl, a delta-arylamino-l,3-but-adienyl, a beta-alkylmercaptovinyl, a beta-arylmercaptovinyl or a beta-acetanilidovinyl group, which vinyl groups may carry a substituent. The condensations are advantageously carried out in the presence of a basic condensing agent, for example a trialkylamine such as triethylamine, a dialkylaniline, a heterocyclic tertiary amine such as pyridine, N-alkyl-pipen'dine or the like.

The new symmetrical cyanine dyes according to the present invention can be prepared by condensing a cyclammonium quaternary salt represented by the general Formula IV above with an ortho car boxylic acid alkyl ester, such as ethyl ortho-formate and ethyl ortho-acetate, advantageously in the presence of a carboxylic acid anhydride, for example acetic anhydride.

The new cyclam-monium quaternary salts represented by the general Formula IV above can further be condensed with a compound represented by the following formula:

wherein: t represents an integer from 1 to 3, Ar represents an aryl group and L and L each represents a methine group. The arylaminovinyl intermediates, or vinylene homologues thereof thus obtained can be transformed into the corresponding acetarylido derivatives by boiling with acetic anhydride, which can be condensed to unsymmetrical cyanine dyes with cyclammoniurn quaternary salts containing a methyl group in alpha or gamma positions to the nitrogen atom. The condensations are advantageously carried out in the presence of a basic condensing agent as set forth above.

The most valuable methine dyes of the present invention are those represented by one of the following general formulae:

: I G C )nl=Cc (=C C il 0(O C )B"l -T wherein n, n", X, Z, Z", R and R" have the same significance as set forth hereinbefore,

R represents a hydrogen atom or a lower alkyl radical such as methy, ethyl and propyl,

d represents a positive integer from 1 to 3, and R' represents a sulphonamide group selected from the group consisting of (CH2-) p1-SO2'I T)C O-alk wherein 1 represents a positive integer from 4 to 5. q represents a positive integer from 2 to 3, and alk represents a lower alkyl radical such as methyl and ethyl, and more particularly those of one of the above general formulae wherein R represents a radical selected from the group consisting of (CH fiSONI-I wherein p, q and alk have the same specifications set forth hereinbefore, R" represents a lower alkyl radical such as methyl, ethyl, propyl, an alkyl radical or a benzyl radical, and a radical of the same type as the radical R, and Z and Z" are the atoms necessary to complete a heterocyclic and nucleus selected from the group consisting of a thiazoline nucleus, 21 selenazolium nucleus, at benzoxazole nucleus, a S-phenylbenzoxazole nucleus, 21 5,6-dimethylbenzoxazole nucleus, at benzothiazole nucleus, a S-methylbenzothiazole nucleus, 21 6-methylbenzothiazole nucleus, at 5,6-dimethylbenzothiazole nucleus, a benzoselenazole nucleus, a 1-ethyl-5,6-dichloribenzimidazole nucleus and a lethyl-5-chlorobenzimidazole nucleus.

The following examples will serve to illustrate further the manner of obtaining our new polymethine dyes.

Example 1 The dyestufl [2-(3ethyl-benzoxazole)1-{2-[3-(omegasulphona-mido-propyl) 4 methyl thiazole]}trimethinecyanine iodide is prepared as follows:

2-(beta-acetanilido-vinyl)-3-ethylbenzoxazolium iodide (1.45 g.), 2,4-dimethyl-3 (omega-sulphonamido-propyl)- thiazolium bromide (1 g.), pyridine (15 cm?) and 1 cm. of triethylamine are heated for ten minutes on the Water bath. The reaction mixture is then poured out in ether in order to precipitate the dyestuff. The latter is purified by recrystallization from ethanol. Absorption maximum: 517 mp.

A silver bromo-iodide emulsion containing per kg. 30 mg. of this dyestufi is strongly sensitized to 600 m with broad maximum at 550 ma.

Example 2 The dyestufi [2-(3-methyl-naphtho-l,2,4,5-thiazole)] {2-[3- (omega-acetylsulphonamido-butyl-)-benzothiazole]} monomethinecyanine bromide is prepared as follows:

A solution of 2-methylmercapto-3methyl-naphtho-1', 2',4,5-thiazolium methyl sulphate (1.8 g.) and Z-methyl- 3-(omega-acetyl sulphonamido-butyl) benzothiazolium bromide (1.8 g.) in ethanol (20 cm?) is treated at C. with 1.4 cm. of triethylamine and shaken for two hours at this temperature. The dyestufi is recrystallized from a mixture of methanol and ethanol. Absorption maximum: 444 mp.

A silver chloride emulsion containing per kg. 20 mg. of this dyestufi' is sensitized to 500 m with a sharp maximum at 480 my.

Example 3 The dyes-tuft {2-[3-(omega-acetylsulphonamido propyl) --phenylbenzoxazo1e] [2-(3-ethyl benzothiazole) trimethinecyanine iodide is prepared as follows:

2-methyl-3-(omega-acetylsulphonamido propyl) 5- phenylbenzoxazolium bromide (4.53 g.) and Z-(beta-acetanilidovinyl)-3-ethylbenzothiazolium iodide (4.5 g.) dissolved in ethanol (20 cm. are treated at 0 C. with 2.8 cm. of triethylamine. After two hours standing at this temperature the dyestulf is precipitated with ether, sucked ofi, dissolved in warm ethanol and treated with a potassium iodide solution. The dyestuff is purified by' recrystallization from ethanol. Absorption maximum: 526 mp.

A silver chloro-bromide emulsion containing per kg. 30 mg. of this dyestulf is strongly sensitized to 615 m with a broad maximum at 560 mu.

Example 4 The dyestutl {2-[3-(omega-ethylsulphonamidobutyl)- benzoselenazole]}[2 (3-ethyl-benzoselenazole)1-mesomethyl trimethinecyanine iodide is prepared as follows:

2 methyl-3-(omega-ethylsulphonamido-butyl)-benzoselenazol-ium bromide (5.8 g.), 2(betamethyl-morcapt0- beta-methylvinyl)-3-ethylbenzoselenazoliurn methyl sulphate (2 g), pyridine (30 0111. and triethylamine (2 cm?) are gently boiled for five minutes, poured out into ether, dissolved in a little ethanol and treated with an aqueous potassium iodide solution. The dyestulf is recrystallized from a mixture of ethanol and methanol. Absorption maximum: 560 mu.

A silver bromo-iodide emulsion containing per kg. mg. of this dyestuff is sensitized to 660 m with a broad maximum at 605-610 m Example 5 The dyestui'f bis {2-[3-(omega-acetylsulponamidobutyl)benzothiazole]}-trimethinecyanine bromide is prepared as follows:

2 methyl 3-(omega-acetylsulponamido-hutyl)-benzothiazolium bromide (4.07 g), ortho-forrnic acid ethyl ester (2.96 g.) and acetic anhydride (10 cm?) are heated for fifteen minutes at boiling temperature. After cooling,

34 I the dyestufi' crystallizes and is purified by recrystallization from ethanol. Absorption maximum: 560 ma.

A silver bromo-iodide emuslion containing per kg. 10 mg. of this dyestutf is sensitized to 665 ma with a broad maximum at 595 m Example 6 The dyestutt (2-{3-[omega-(N-methylsul pho-sulphonamido) pro pyl] -benzothiazole} -[2-(3-ethyl-thiazoline) triethine cyanine bromide is prepared as follows:

2 methyl 3-ornega-(Nmethylsulpho-sulphonamido)- propylpropylbenzothiazolium bromide (4.29 g.) and 2- (beta-acetanilido-vinyl)-3-ethylthiazolium bromide (3.55 g.) in ethanol (10 cm?) are treated at 0 C. with triethylamine (2.8 cmfi). After standing for one hour at this temperature the dyestuff is sucked off and recrystallized from ethanol. Absorption maximum: 504 mu.

A silver bromide emulsion containing per kg. 15 mg. of this dyestufr" is sensitized to 590 m with a maximum at 540 ma.

Example 7 The dyestufif [2-(3-methyl-naphtho-l,2,4,5-thiazole)]- {2 [3 (N-methylsulpho-carbamyl-methyl)-benzothiazole]}monomethine cyanine bromide is prepared as follows:

2 methylmercapto-3-methyl-naphtho-1,2,4,5-thiazolium methylsulphate (3.6 g.) and 2-methyl-3-(N-methylsuphocarbamyl)-methyl)-benzothiazolium bromide (3.6 g.) are dissolved in ethanol (30 cm?) and after cooling at 0 C. trimethylarnine (2.8 cm?) is added dropby drop. After standing for two hours at the same temperature the crystallize dyestuif is sucked oil and recrystallized from diluted ethanol. Absorption maximum: 444 mp.

A silver chloride emulsion containing {per kg. 15 mg. of this dyestuit is sensitized to 500 mg with a sharp maximum at 480 m Example 8 The dyestufl bis-{2-[3-(N-ethylsulpho-carbamyl-methyl)-benzothiazole]}mesomethyl trimethine cyanine bromide is prepared as follows: 7

2 methyl-3-(N-ethylsulpho-canbamyl-met-hyl)-benzothiazolium bromide (3.79 g), ortho-acetic acid ethyl ester (3.24 g.) and pyridine (25 cm?) are held for ten minutes at boiling temperature. On cooling, the dyestuil crystallizes partly, and after complete precipitation with ether is purified by recrystallization from ethanol. Absorption maximum: 546 ma.

A silver bromo-iodide emulsion containing per kg. 10 mg. of this dyestutt" is sensitized to 660 m with a broad maximum at 600 ma.

Example 9 The dyestufi {2-[3-(N-methylsulpho-carbamyl-methyl)- benzoselenazole] [2 3-ethyl-benzothiazole) ].mesomet-l1- yl trimethine cyanine bromide is prepared as follows:

2 methyl-3(N-methyl-sulphocarbamyl-methyl)-benzoselenazolium bromide (4.12 g.) and Z-(beta-rnethyl-betamethylmercapto vinyl)-3-ethyl-benzothiazolium methyl sulphate (3.61 g.) are dissolved in ethanol (50 cm. cooled at 0 C. and treated with trimethylamine (2.8 cmfi). After standing for two hours at 0 C. the dyestufl is sucked olf and recrystallized from ethanol. Absorption maximum: 550 m A silver bromo-iodide emulsion containing per kg. 10 mg. of this dyestufi is sensitized to 670mm with a broad maximum at 605 ma.

Example 10 The dyestuff bis (2-{3-[beta-(N-methyl-sulpho carbamyl -e thyl] -benzo selenazole} -trimethine cyanine bromide is prepared as follows:

2 methyl-3-[beta-(N-methylsulphocarbamyl)-ethyl]- benzoiselenazoli-um bromide (4.26 g), ortho-formic acid ethyl ester (2.96 g.) and acetic anhydride (25 cm?) are 15 held for fifteen minutes at boiling temperature. On cooling, the dyestulf crystallizes and is purified by recrystallization from methanol. Absorption maximum: 576 m silver 'bromo-iodide emulsion containing per kg. 10 mg. of this dyestuif is sensitized to 670 m with a broad maximum at 605610 m Example 11 The dyestuii 2- 3- [beta- (N-methylsulpho-carb amyl ethyl] -benzothiazole} 2 (3-ethyl-benzoxazole -trimethine cyanine iodide is prepared as follows:

A solution of 2-methyl-3-[ beta-(N-methyl-sulpho-ca1rbamyl)-ethyl] benzothiazolium bromide (3.79 g.) and 2- (beta-acetanilido-venyl) 3 ethyl-benzoxazolium iodide (4.34 g.) in ethanol (50 cm?) is cooled at C., treated with triethylamine (2.8 crn. and stirred at this temperature for two hours. The dyestuff is sucked off, dissolved in warm ethanol, treated with a potassium iodide solution and recrystallized from ethanol. Absorption maximum: 522 m A silver bromide emulsion containing per kg. 20 mg. of this dyestuff is sensitized to 600 m with a broad maximum at 560 m Example 12 The dyestuff {2-[3-(N-methylsulpho-carbamyl-methyl)- 5,6 dimethyl benzothiazole}]-[2-(3-ethyl-benzothiazole) ]-tr.imethine cyanine iodide is prepared as follows:

2,5,6 trimethyl 3 (N methylsu lp'ho carb-amylmethyl)-benzothiazolium bromide (3.93 g.), 2-(betaacetanilido-vinyl)-3-ethylbenzothiazolium iodide (4.50 g.), ethanol (50 cm. and tr-iethylamine (2.8 cm. are heated for fifteen minutes at boiling temperature. After cooling the dyestuif crystallizes and is further purified by recrystallization from ethanol. Absorption maximum: 568 m A silver bromo-iodide emulsion containing per kg. 20 mg. of this dyestutf is sensitized to 670 m with a broad maximum at 605-610 mp.

Example 13 The dyestutf {2-[3-(N-methylsulpho-carbaimyl methyl)- phenylbenzoxazole]}[2 (3 ethylbenzothiazole)]- trirnetlhine cyanine iodide is prepared as follows:

2 methyl 3 (N methylsulpho carba-my-l methyl)- S-phenylbenzoxazolium bromide (4.25 g.), 2-(betaacetanilidovinyl) 3 ethylbenzothiazolium iodide (4.50 g.) and acetic anhydnide (25 cm?) are treated with trieth-ylamine (2.8 cm?) and held for ten minutes at boiling temperature. The dyestuff which crystallizes on cooling is recrystallized from ethanol. Absorption maximum: 526 mp.

A silver bromide emulsion containing per kg. 30 mg. of this dyestuff is strongly sensitized to 620 m with a broad maximum at 5 60 m Example 14 The dyestufi bis {2 [3 (beta methylsulphonylamino ethyl) benzothiazole1} trimethine cyanine bromide is prepared as follows:

A solution of 2-methyl-3-(beta methyl-sulphonylamino-ethyl)-benzothiazolium bromide (7 g.) in pyridine (30 cm?) is refluxed for thirty minutes with ethyl-orthoformate (7 @1113). The dyestuff is precipitated with a potassium bromide solution and twice recrystallized from ethanol. Absorption maximum: 563 m A silver bromo-iodide emulsion containing per kg. mg. of this dyestuff is sensitized to 665 m with a broad maximum at 595 mp.

Example 15 The dyestufi {2 [3 (beta methylsulphonylaminoethyl) benzothiazolej} [2 (3 ethyl thiazoli-ne)]- trimeth-ine cyanine bromide is prepared as follows:

Triethylamine (2.1 cm?) is added to a cooled solution of 2 methyl 3 (beta methylsulphonylamino ethyl)- benzothiazolium bromide (5.3 g.) and 2-beta-acetanilid-oviny-1)-3-ethyl thiazolinium bromide (5.3 g.). The precipitated dyestult is washed with ethanol and ether and crystallized from ethanol. Absorption maximum: 501 m A silver chloro-bromide emulsion containing per kg. 15 mg. of this dyestuff is sensitized to 580' m with a maximum at 540 mp.

Example 16 The dyestufi [2 (3 henzyl benzoxazole)]{2 [3- (N methylsulp'ho carbamyl methyl) 4 methylth-iazol-e1} trimethine cyanine iodide is prepared as follows:

2,4 dimethy-l 3 (N methylsulpho carbamyimethyl) thiazolium bromide (1.64 g.) and 2 (betaanilido-v-inyl)-3-benzyl-benzoxazolium bromide (2 g.) are heated for ten minutes in pyridine (15 cm. acetic anhydride (2 cm?) and triethylamine (1.4 cm. The reaction mixture is then poured out in ether; after treating with sodium iodide the dyestufi is purified by recrystallization from ethanol. Absorption maximum: 514 m A silver bromo-iodide emulsion containing per kg. 30 mg. of this dyestuif is strongly sensitized to 600 m with a broad maximum at 555 m Example 17 The dyestufi {2 [3 (N methylsulp ho carbamylmethyl) 5 methylbenzothiazole]}[2 (3 propyl- -thiazo1ine)]-trimethine cyanine bromide is prepared as follows:

2 methyl 3 (N'- methyl su-l-p-ho carbamyl-methyl)- 5 methyl benzothiazolium bromide (3.8 g.) and 2- (beta acetanilido vinyl) 3 propyl tniazoli-nium bromide (5.2 g.) are dissolved in methanol (25 cm?) and are treated at 0 C. with trieth-ylamine (2.8 cm. After standing for ninety minutes at this temperature, the dyestuff is precipitated in ether, sucked off and recrystallized from ethanol. Absorption maximum: 509 mp.

A silver bromide emulsion containing per kg. 8 mg. of this dyestufi is sensitized to 585 m with a maximum at 545 mp.

Example 18 The dyestufi [2 (3 ethylbenzoxazole)]{2 [1- ethyl 3 (omega acetyl sulphonamido butyl) 5,6- dichlor-o-benzimidazole1}-trimethine cyanine iodide is prepared as follows:

1 ethyl 2 methyl 3 (omega acetyl sulphonamido butyl) 5,6 dichloro benzimidazolium bromide (4.9 g.) and 2-(meta-acetanilidovinyl)-3-ethyl-benzoxazolium iodide (4.4 g.), acetic anhydride (30 cm. and triethylamine (2.8 cm?) are heated for one hour at boiling temperature. The dyestufr is precipitated with ether and is recrystallized from a mixture of diacetone alcohol and ethanol. Absorption maximum: 490 m A silver bro-mide emulsion containing per kg. 17 mg. of this :dyestufi is sensitized to about 600 m with a sharp maximum at 547 m Example 19 The dyestufi bis{2 [3 (N methylsulpho carbarnylethyl) 5 'chloro benzothiazole1} trimethine cyanine bromide is prepared as follows:

2 methyl 3 (N methylsulpho carbamyl ethyl)- 5 ch'loro benzothiazolium bromide (4.1 g.), ethylortho-formate (2.96 g.) and pyridine (25 cm?) are brought for live minutes at boiling temperature. The dyestuif crystallizes, is sucked off and is purified by recrystallization from a mixture of phenol and ethanol. Absorption maximum: 570 mp.

A silver bromo-iodide emulsion containing per kg. 20 mg. of this dyestufi" is sensitized to about 675 m with a maximum at 610 m Example 20 The dyestuif {2 [3 (omega acetyl-sulphoamido-propyl) 6 methylbenzothiazole]}[2 (3 ethyl selenazoline)]-trimethine cyanine iodide is prepared as follows:

2,6 dimethyl 3 (omega acetyl sulphonamidopropyl)-benzothiazolium bromide (4.1 g.) and Z-(betaacetanilido-vinyl)-selenazolium ethyl iodide (4.5 g.) are treated at C. in methanol (30 cm?) with triethylamine (2.8 cm.-'*). After standing for one hour at this temperature the dyestufi is precipitated with ether, sucked off and recrystallized from ethanol and water. Absorption maximum: 510 mp.

A silver chloride emulsion containing per kg. 20 mg. of this dyestull' is sensitized to 570 m with a maximum at 545 mp.

Example 21 The dyestufi bis {2 [3 (omega acetyl-sulphoamidopropyl) 5 phenyl benzoxazole]}meso propyl trimethine cyanine iodide is prepared as follows:

2 methyl 3 (omega acetyl sulphonamido propyl)-5-phenyl-benzoxazolium bromide (1 g.), ethyl'ortho butyrate (ll cm?) and pyridine (1 cm. are heated for ninety minutes at boiling temperatures. After cooling, the dyestufif is precipitated with ether, dissolved in ethanol and treated with a solution of sodium iodide in methanol. The dyestutf is recrystallized from ethanol. Absorption maximum: 506 m A silver bromide emulsion containing per kg. 15 mg. of this dyestutf is sensitized to 580 m with a maximum at 555 mp.

Example 22 The dyestufi {2 [3 (omega diacetyl sulpho hydrazido butyl) benzothiazole]}[2 (3 ethyl thiazoline)-trimethine cyanine bromide is prepared as follows:

2 methyl 3 (omega diacetyl sulpho hydrazidobutyl)-benzothiazolium bromide (3.5 g.) and Z-(betaacetanilidovinyl)-3-ethyl-thiazolinium bromide (2.7 g.) are dissolved in methanol (20 cm?) and after treating with triethylamine (2.1 cm.-") placed in an ice bath for two hours. The dyestutf precipitates, is sucked off and is crystallized three times from ethanol. Absorption maximum: 504 m A silver chloride emulsion containing per kg. 8 mg. of this dyestufi is sensitized to 570 mp with a maximum at 540 mp.

Example 23 The dyestufi {2 [3 (omega acetyl sulphonamidobutyl) 5,6 dimethyl benzoxazole1} {2 [3 (N- methylsulpho carbamyl methyl) 5,6 dimethyl benzoxazole]}-trimethine cyanine bromide is prepared as follows:

2,5,6 trimethyl 3 (N methylsulpho carbamylmethyl)-benzoxazolium bromide (2.4 g.), 2-(beta-anilido vinyl) 3 (omega acetyl sulphoamido butyl) 5,6- dimethyl-benz xazolium bromide (2.6 g.), acetic anhydride (20 cm?) and triethylamino (1.4 cm?) are refluxed for 1 hr. After cooling, the dyestuff is precipitated with ether and purified by crystallization from ethanol. Absorption maximum: 501 mp.

A silver bromide emulsion containing per kg. 30 mg. of this dyestuff is sensitized to 555 m with a maximum at 520 mp.

Example 24 The dyestuff anhydro{2 [3 (omega acetyl sulphonamido butyl) 5,6 dimethyl benzoxazolefi {2- [3 (sulpho carbomethoxymethyl) benzothiazole]}-trimcthine cyanine hydroxide is prepared as follows:

2 (beta anilino vinyl) 3 (omega acetyl sulphonamido butyl 5,6 dimethyl benzoxnzolium bromide (2.6 g.), 2-methyl-3-(sodium-sulphocarbomethoxymethyl)-benzoxazolium bromide (2 g.), acetic anhydride (20 cm?) and triethylamine (1.4 cm. are refluxed for /5 hour. After cooling, the dyestuif is precipitated with ether and recrystallized from ethanol. Absorption maximum: 526 m A silver bromo-iodide emulsion containing per kg. 30 mg. of this dyestuff is sensitized to 600 m with a maximum at 560 mp.

Example 25 The dyestufi bis{2 [3 (omega acetyl sulphonamido butyl) benzothiazole]}pentamethine cyanine bro mide is prepared as follows:

2 methyl 3 (omega acetyl sulphonamido butyl)- benzothiazolium bromide (8.14 g.), 1-anilino-3-phenylimino-propenylidene hydrochloride (2.6 g.) acetic anhydride (30 cm?) and triethylamine (2.4 cm?) are refluxed for 95 hour and cooled. The dyestuff is precipitated by ether and recrystallized from ethanol. Absorption maximum: 654 m A silver chloride emulsion containing per kg. 6 mg. of this dyestuff in the presence of 10 g. of l-hydroxy-Z- stearoylamino-naphthalene-sulphonic acid is sensitized to 760 m with a maximum at 700 m Example 26 The dyestuff {2 [1 beta methyl sulphonylaminoethyl) quinolinel} [2 (3 methyl benzothiazole)] monomethine cyanine bromide is prepared as follows:

1 (beta methyl sulphonylamino ethyl) quinolinium bromide (2.6 g.) 2-methylmercapto-3-methyl-benzothiazolium-tolusulphonate (2.3 g.), pyridine (50 cm. and triethylamine (1.1 cm. are refluxed for minutes and cooled. The dye is precipitated by ether, washed with methanol and recrystallized from ethanol. Absorption maximum: 486 m A silver bromo-iodide emulsion containing per kg. mg. of this dyestufi is sensitized to 560 m with a maximum of 540 m Example 27 The dyestufi [2 (3 ethyl benzoxazole)] {2 [3- (dimethyl aminosulphonyl carbamyl methyl) l" zothiazolel} trimethine cyanine iodide is prepared as 1 lows:

2 methyl 3 (dimethylamino sulphonyl carbamylmethyl) benzothiazolium bromide (2 g.), 2 (betaacetanilido-vinyl)-3-ethyl-benzoxazolium iodide (2.17 g.), ethanol cm?) and triethylamine (1L4 cm?) are refluxed for 15 minutes. On cooling, the dye crystallizes and is purified by recrystallization from ethanol. Absorp tion maximum: 526 mp.

A silver bromo-iodide emulsion containing per kg. 30 mg. of this dyestuff is sensitized to 600 m with a maximum at 560 mp.

Example 28 The dyestuif bis{2 [3 (dimethyl amino sulphonylcarbamyl-methyl)-benzothiazole]} mesomethyl trimethine cyanine iodide is prepared as follows:

2 methyl 3 (dimethylamino sulphonyl carbamylmethyD-benzothiazolium bromide (5.9 g.), methyl-orthoacetate (5.9 cm) and pyridine cm?) are refluxed for 56 hour, cooled, diluted with water, treated with an aqueous potassium iodide solution, evaporated, and extracted with hot phenol. On cooling and dilution with ethanol, the dye precipitates. It can be purified by recrystallization from a mixture of phenol and ethanol. Absorption maximum: 549 mp.

A silver bromo-iodide emulsion containing per kg. 15 mg. of this dyestufl' is sensitized to 650 m with a maximum at 595 mp.

Example 29 The dyestufl {2-[3-ethyl-4-(3-ethyl-dihydro-benzothiazolylidene-ethylidene)-5-thiazolione]) (2-[3-(be-ta-mcthyl sulphonylamino ethyl) benzothi-azolel} monomethine cyanine bromide is prepared as follows:

[2-(3-ethyl-benzothiazole)]-[4 (2 methylmercapto- 3-ethyl-5-thia1olinone)] dimethine merocyanine methyl sulphate (4.75 g.), 2-methyl-3-(beta-methyl-sulphonylamino-ethyl)-benzothiazolium bromide (3.5 g.), ethanol 19 (30 cm?) and triethylamine (1.4 cm. are refluxed for minutes. After cooling, the precipitated dye is filtered ofi and crystallized from a mixture of phenol and ethanol. Absorption maximum: 611 m A silver bromo-iodide emulsion containing per kg. 15 mg. of this dyestuff is sensitized to 710 my. with a broad maximum at 660 m As shown in the above examples, the new polymethine dyes spectrally sensitize photographic silver halide emulsions when incorporated therein. Although the new polymcthine dies are useful especially for extending the spectral sensitivity of the customarily employed gelatino silver chloride, gelatino silver chloro-bromide, gelatino silver bromide, gelatino silver bromoiodide and gelatino silver chloro-bromo-iodide emulsions, photographic emulsions containing water-permeable colloids other than gelatin, such as agar-agar, zeine, collodion, water-soluble cellulose derivatives, polyvinyl alcohol or other hydrophilic synthetic or natural resins or polymeric compounds, may equally well be sensitized according to the present invention.

To prepare photographic emulsions sensitized according to the invention with one or more of the new polymethine dyes, the dye, or dyes can be incorporated in the photographic emulsion by one of the methods customarily employed in the art. In practice, it is convenient to add the dyes to the emulsion in the form of a solution in an appropriate solvent. The dyes are advantageously incorporated in the finished, washed emulsions and should be uniformly distributed throughout the emulsion. The concentraiion of the dyes in the emulsion can vary widely, for example from 1 to 100 mg. per kg. of fiowable emulsion and will vary according to the effect desired. The suitable and most economical concentration for any given emulsion will be apparent to those skilled in the art, upon making the ordinary tests and observations customarily used in the art of emulsion making.

The new polymethine dyes can be incorporated in photographic emulsions the general sensitivity of which has been increased by physical and chemical ripening. As suitable chemical sensitiners may be mentioned the well known sulphur sensitizers such as allylisothiocyanate, allylthiourea, sodium t-hiosulphate, potassium selenocyanide and the natural sensitizers originating in the gelatin, reducing sensitizers such as the imino-aminomethane sulphinic acid and the derivatives thereof, and the salts of noble metals such as gold, platinum and palladium.

The photographic emulsions optically sensitized according to the invention may further be supersensitized and/or hypersensitized by one of the methods known to those skilled in the art.

In preparing the photographic emulsions according to the invention, the usual addenda such as antifogging agents, stabilizers, anti-bronzing agents, hardeners, wetting agents, plasticizers, development aocelerators, color couplers, fluorescent brighteners and ultra-violet screening compounds can moreover be incorporated in the emulsion in the manner customarily employed in the art. In this respect it may be mentioned that the sensitivity of the silver halide emulsions sensitized according to the process of the present inventionis not adversely affected but rather enhanced by the presence therein of certain fluorescent compounds. Another advantage of the process for sensitizing silver halide emulsions according to the present invention is the compatibility of the new polymethine dyes with anionic wetting agents and with color couplers which is of great importance in the application of the new polymethine dyes for sensitizing the silver halide emulsions of a light-sensitive element for color photography.

Emulsions sensitized with the new polymethine dyes can be coated in the usual manner on a suitable support such as glass, cellulose derivative film, resin film or paper.

We claim.

1. A eyanine dye of the formula:

0 I J-clI=oIt--or1=o N, \N I t)r- Os- CO-CH; 3 11; 2. A eyanine dye of the formula:

N (JJHI)F'SOINHCIII| (Ja a 3. A eyanine dye of the formula:

J t)s- :-NHBOPC r 4311b 4. A eyanine dye of the formula:

(1, Misti Q N N ()Hr-CO-NH-SOg-Czfi; hnrco-Nn-soi-cin 5. A eyanine dye of the formula:

cl N-Cflh o c1I=cHcIt=(L I- (CHgh-SOr-NH-CO-CH; 1111 References Cited by the Examiner UNITED STATES PATENTS 2,778,823 1/ 1957 Brooker et al 260240.6 2,899,430 8/1959 Sprague 260--240.4 2,905,666 9/1959 De Stevens 26024O 2,912,433 11/ 1959 Sprague 260240 2,912,434 11/1959 De Stevens et al. 260-250.1 2,916,487 12/ 1959 De Stevens 260-2404 2,916,488 12/ 1959 De Stevens 260-7A0.4 2,973,264 2/ 1961 Nys et al 260-2406 X 3,058,978 10/ 1962 Berlin et al. 260-2406 3,071,467 1/1963 Rauch 260--240.4 X

JOHN D. RANDOLPH, Primary Examiner. 

1. A CYANINE DYE OF THE FORMULA: 2-((3-(C2H5-)-2,3-DIHYDRO-2-BENZOTHIAZOLYL)=CH-CH=CH-), 3-(CH3-CO-NH-SO2-(CH2)3-),5-PHENYL-BENZOXAZOLIUM I(-) 